Distinct immune responses to HIV and CMV in Hofbauer cells across gestation highlight evolving placental immune dynamics

Placental immune responses to Human Immunodeficiency Virus (HIV) and Human Cytomegalovirus (CMV) vary across gestational stages and may influence postnatal outcomes. This study investigates the innate immunity of Hofbauer cells from placentae obtained at early/mid-gestation (18-21.6 weeks) and term (>37 weeks). RNA sequencing and cytokine profiling reveal that early/mid-gestation HCs exhibit heightened differential gene expression responses compared to term HCs, indicating a distinct transcriptional activity in early pregnancy. Significant overlap in gene expression profiles of early/mid-gestation cells in response to CMV and HIV suggest similar innate immune responses, while term cells exhibit distinct patterns, reflecting the temporal evolution of placental immunity. Integration with Human Protein Atlas database reveals more placental-specific differentially expressed genes in early/mid-gestation HCs exposed to HIV and CMV compared to term cells. Functional analysis reveals downregulation of pathways related to oxygen stress, estrogen response, and KRAS signaling pathway in early/mid-gestation HCs, with HIV uniquely upregulating reactive oxygen species and CMV uniquely disrupting WNT {beta}-Catenin signaling. In term HCs, CMV exposure upregulates antiviral interferon (IFN) signaling and inflammatory pathways. Co-expression analysis highlights distinct molecular pathway enrichments across gestation, particularly with upregulation of IFN signaling and disruption of lipid metabolism in term CMV-exposed HCs. Cytokine profiling shows enhanced expression of GM-CSF, IFN-{gamma}, and Th2-associated cytokines in early/mid-gestation HCs, indicating heightened immune responsiveness. These findings reveal the dynamic nature of placental immunity and underscore the need for targeted interventions to address unique immune and metabolic disruptions caused by viral infections at distinct stages of pregnancy to improve fetal and infant health outcomes.